Plant thinning machine



C. B. RICHEY PLANT THINNING MACHINE June 22, 1954 Filed Oct. 5, 1950.A'A'A. u v v v Patented June 22, 1954 PLANT THINNING MACHINE ClarenceB. Richey, Royal Oak, Mich., assignor,

by mesne assignments, to Ford Motor Company, Dearborn, Mich, acorporation of Delaware Application October 3, 1950, Serial No. 188,201

8 Claims.

This invention relates to an improved method and apparatus for thinningthe stand of plants of row crops to an optimum spacing.

In general, it is common practice to plant a greater number of seed forvarious row crops than is actually required. Such procedure is necessarydue to the inherent inability of planting machines to precisely plantthe seed and because of the uncertain germination of the seed. One suchcrop is cotton where the seed does not lend itself readily to precisionplanting and germination varies greatly with weather and soilconditions.

Obviously, if a thickly seeded row of plants is not thinned to anoptimum spacing, the majority of the plants will not mature properly asa result of too much crowding. Plant thinning heretofore has beenlargely done by hand and such a procedure i not only laborious butexceedingly costly. While, of course, there have been plant thinningmachines devised for reducing the plant stand, such prior machines thinthe plant stand with mechanical precision which leaves the plants at adesired spacing but does not consider size or sturdiness of either theplant left or those removed. It is well known that the more vigorousplants will generally outstrip a weaker one and that such a vigorousplant will not only grow larger, but will produce a higher yield of thecrop which it bears. It is obviously undesirable to arbitrarily removeall of these healthy, vigorous plants just because they do not happen tobe located at the position in the row of the saved plants.

Accordingly, it is an object of this invention to provide an improvedmethod and machine for reducing the plant stand in a row to an optimumnumber of plants.

Another object of this invention is to provide a method of plantthinning and a plant thinning machine which will thin or reduce a plantstand to a desired number of plants and which will also selectivelyremove only the smallest or Weakest plants of the plant stand.

A further object of this invention is to provide a plant thinningmachine of simple, rugged design Which may bereadily and cheaplymanufactured;

Thespeciflc nature ofthis invention, aswell as other objects andadvantages thereof, will become apparent tothoseskilled in the art fromthe following detailed description, taken in conjunctionwith theattached: she'etof drawings on which, by way of preferred example only;illustrated oneembodiment of thisinvention:

On the drawings:

Fig. 1 is a side elevational view of the plant thinning device shownmounted on a tractor.

Fig. 2 is an enlarged, detail, longitudinal, sectional view of thehydraulic cylinder control.

Fig. 3 is an enlarged, fragmentary view of Fig. 2 showing the checkvalve in detail. a

Fig. 4 is a partial sectional view taken on the plane 4-4 of Fig. 1.

Fig. 5 is a schematic diagram showing the wiring arrangement forelectrically connecting the various elements of the improved plantthinning device.

As shown on the drawings:

The improved method or" plant thinning provided by this invention may bedescribed in gen eral terms as follows. A plant removing apparatus ofany well known type is operated along a row of plants so as to removeeach successive plant in the row unless a plant selecting deviceoperates to render the plant thinning apparatus temporarily inactive forsufficient time to pass the selected plant. The plant selecting ordetecting device operates entirely in response to the height of thesuccessive plants in the row. However, the effective plant height; forproducing response of the plant selecting mechanism is cyclically variedin a saw tooth pattern, i. e., after each operation of the plantdetecting mechanism, the response height is abruptly changed to amaximum height level above the average plant height; then the plantresponse height is gradually decreased from such maximum height to aminimum height over a distance of travel corresponding approximately tothe desired spacing between plants after the thinning operation. Hence,if all of the plants are of uniform height, the minimum response heightfor the plant selecting device is adjusted to slightly less than theaverage height of the successive plants and the plant selecting devicewill function only when it reaches that point of its vertical positioncycle which corresponds to the height of the particular plant to whichit is adjacent. When the plants are of non-uniform height, which isgenerally the situation, an unusually tall plant will activate the plantselecting device even though it is located less than the desired spacingdistance from the preceding plant. It is to be understood that the plantselecting device is automatically reset to its maximum height positionafter each actuation, thus providing a cyclically varying verticalposition of the plant selecting apparatus as the plant thinning machineis traversed along the row of plants.

In Fig. 1 there is shown a plant thinning device constructed to carryout the method of this invention. Briefly, the plant thinning device ismounted on a tractor indicated generally by the numeral 16 and comprisesa plant removal device such as a wheel type hoe H rotatably mounted on abracket i2 secured to a frame structure 53. A plant selecting device,here shown as an electric eye or photo-electric cell unit it is mountedon an arm pivoted to frame It and vertically lifted by a solenoid It toprovide variation of the plant response height of such unit. Such eye isgradually lowered to within close proximity of the plants by a hydrauliccylinder control 28 which drops the arm 2'! at a predetermined rate.When the light beam of photo-cell unit if; is interrupted either by aplant taller than the average or when dropped the full limit by thecylinder 28 and interrupted by an average height plant, suchphoto-electric unit actuates a solenoid operated detent I l to releasehoe l i to permit such hoe to rotate in order to save a plant.Simultaneously, photo-cell unit it is raised by solenoid it toreposition such eye for repeating the cycle.

The plant thinning device constructed in accordance with this inventionwill now be described in greater detail. A transverse tool bar H issecured to the front end of tractor ill by suitable brackets l8 securedto the tractor main frame Hid by a plurality of bolts i811. A verticalbracket 2%] is welded or otherwise secured to the end of tool bar H asshown in Fig. 1 and such bracket pivotally supports a pair of rearwardlyprojecting vertically spaced, parallel link members 2!. Links 2! arepivotally connected at vertically spaced points in suitable fashion to avertical frame I3 as shown in Fig. 1. Frame [3 of the plant thinningdevice comprises a vertical channel or angle iron member having abifurcated lower end 130. and a ground engaging wheel 19 rotatablymounted to such lower end by a transverse mounting pin 911. The linkmembers 2! permit frame it to raise or lower vertically as the groundwheel i9 follows the ground contour.

A bracket E2 of tubular construction is horizontally secured'to frame itas by welding. A

gusset plate i2a welded respectively to frame 13 and bracket 32reinforces the juncture of these two members. Hoe wheel H comprises aflat disc hub portion Ila. having a plurality of radially projecting,evenly spaced bar-like arms lib secured thereto by rivets l Ic. Ahoe-like blade I id is welded to the outer end of each arm lib as shownin Fig. 1. Blades ild are preferably of triangular configuration and areso disposed on the ends of arms lib that when the blade contacts theground, such blade will be substantially parallel with the ground andwill ride on or below the ground surface as shown in Fig. 1. Blades lidare provided for thinning the plant stand as will be later described.

Disc i la is secured by welding to a shaft 22 which is journaled in atubular shaft housing 23. Housing 23 is angularly disposed relative tobracket l2 and is downwardly directed as shown in Fig. 1. Shaft housing23 is secured by welding to a mounting plate 24 welded to the top ofbracket [2 as shown in Fig. 1. A circular plate 25 is suitably securedto the other end of shaft 22 and circular plate 25 abuts the upper endof shaft housing 25 thereby rotatably securing hoe wheel and shaftassembly to housing 23. A plurality of radially disposed, equally spacednotches 25 1 are provided about the periphery of disc 25 which areengageable by a solenoid operated detent member as will now bedescribed.

A plate-like standard 26 is vertically secured by welding to bracket l2forwardly of disc 25 and a shelf member 26a is horizontally secured bywelding to the top of standard 2'6. Shelf 26a. projects rearwardly to apoint adjacent the disc 25 and solenoid M. is suitably secured to shelf26a. Solenoid M has a rearwardly projecting armature [4a on the end ofwhich there is secured a detent member [42) which is selectiyelyengageable with any of the notches 25a in disc 25. Armature Ida isspring biased outwardly to normally maintain detent Mb in engagementwith notch 25a. Energization of solenoid l4 retracts armature Ma todisengage detent Mb from the notch 25a to permit rotation of hoe wheel Has will be later described.

An electric eye or photo-electric cell unit I5 is mounted on an arm 2!comprising a pair of barlike members which are pivotally secured toframe it in transversely spaced relationship as by a bolt 27a as shownin Figs. 1 and 4. Arm 2'! slopes downwardly from frame [3 as shown inFig. 1 and a photo-cell 15a is suitably fastened to one side of thelower end of arm 21. A light source 15b comprising any conventionallight bulb capable of emitting a light beam is suitably secured to theopposite side of arm 2"! as shown at 15b (Fig. 4). Light source 152) isso positioned on such arm that light beam therefrom will be interceptedby photo-electric cell unit i5. Arms 21 are vertically lifted bysolenoid It connected to bracket l2 and arms 27. An eye bolt member lGaintegrally provided on the lower end of solenoid iii permits pivotalmounting of such solenoid to arm 2? by a transverse bolt [6b. Thearmature ific of solenoid It projects upwardly and terminates in an eyeportion Hid. A bolt Hie cooperable with eye ltd pivotally mounts theupper end of solenoid it to bracket it. When solenoid it is energized,armature 56c is drawn into solenoid l6 whereby arm 2? is raised carr ingwith it unit i5 for a purpose to be later explained.

After arm 2? is raised by solenoid [6, arm 21 must then be lowered todrop electric eye 15 and light source i5?) respectively adjacentopposite sides of a row of plants so that the light beam of such lightsource will be partially interrupted by the top portions of theimmediately adjacent plant to actuate the solenoids M and it, whichtemporarily renders hoe i i inoperative and raises photo-electric unit I5 up to its pre-selected maximum height. Such upward movement restoresphoto-cell unit it to normal energization and hence de-energizessolenoids Hi and it. To control the lowering movement of photo-cell unit15, there is provided a single acting hydraulic cylinder 28 which ispivotally connected to and is disposed between arms 21' and bracket l2.A piston 28a cooperates with cylinder 28 and such piston has adownwardly projecting piston rod 28b. An eye 280 is formed in the lowerend of piston rod 281) and such eye is pivotally secured to arm 27 by atransverse bolt or pin 28d.

An integral axial, tubular portion 28c is pro vided on top of cylinder28 and an eye bolt member 29 provided with a stem portion Zita isutilized for pivotally mounting the upper end of cylinder 28 to bracketi2, transverse bolt 2% effecting such connection. Stem portion 290, ofeye member 29 cooperates with the bore of tubular portion 286 and suchmember is locked in a desired position of longitudinal adjustment by a,set screw 30 which is radially disposed in a thickened portion of thewall of tubular portion 280 as shown at 30a. This telescoping connectionbetween the cylinder and the eye member 29 enables arm 21 to be adjustedvertically to adjust the maximum height of electric eye unit [5 abovethe ground dependent upon the average height of the plants as will belater described.

Hydraulic cylinder 28 as was previously mentioned, acts in only onedirection and is in effect a dashpot and is utilized to lower arm 2'! ata predetermined rate following each raising by solenoid at. In order forcylinder 28 to so function, a bleed hole 28f is provided in piston 28dthrough which the hydraulic fluid contained in cylinder 28 can flowslowly. Thus when arm 2'! is lowered,

the weight of such arm moves piston 231a downwardly and forces thehydraulic fluid contained in the lower portion of cylinder 28 as shownat 239 to flow upwardly through bleed hole 28/ thereby permitting arms21, with electric eye I5 mounted thereon, to lower at a predeterminedrate of speed. Varying the diameter of hole 28 will, of course, vary therate of drop of arm 21. The rate of fall is selected as a function ofthe ground speed of the carrier ll] so that photo-cell unit l5 fallsfrom the selected maximum height level to the average level of theplants while the carrier ill moves a distance equal to the desired plantspacing.

When arm 27 is raised, it is necessary that the dampening effect ofcylinder 28 be voided to permit the rapid raising of arm 27 by solenoid15. This end is accomplished by a ball type check valve 3|. A transversehole 3la is provided in piston 23d and such hole is counterbored asshown at 3 lb. The bottom of counterbore 3th is of conical configurationas shown at 31c and ball valve 3i rests in the bottom of the cone shapedportion 310 of counterbore 31b and obstructs opening 3 la. Ball checkvalve 3! is yieldingly held there by a helical spring 32 and spring 32is retained in position by a plug 33 screwed into a threaded end portionof counterbore 3!?) as best shown in Fig. 3. A plurality of portstitaare provided in plug 33 to enable the hydraulic fluid passing byball check valve 3| to escape to. the lower portion 28g of hydrauliccylinder 28.

In Fig. 4 there is illustrated a schematic wiring diagram wherein Pindicates a suitable power source provided on the tractor 10.Photoelectric cell l5a is connected to the input of a trigger typeamplifier 34.. Amplifier- 34 may be of any one of several well knowntypes which is so connected to photo-electric cell Ida so as to normallyproduce no power output to its load, represented by the coil of a relay35, so long as photo-electric cell a is fully energized by light beamsfrom the light source I52 Upon a decrease in the amount of lightimpinging upon photoeelectric cell [5a, trigger amplifier 34 is actuatedto supply suflicient current to the coil of. relay 35 to operate suchrelay to close the Circuit through the contacts 35a. The solenoids l4and It are respectively connected in parallel and are supplied frompower source P through a circuit which includes the relay contacts 35ain series. Hence, the solenoids l4 and 16 are only energized so long asthere is any decrease in the intensity of light impinging uponphotoelectric cell 4 5a. To facilitate the starting of the entireapparatus, a manually operated by-pass switch 36 is connected inparallel with the contacts 35a of relay 35. Hence, the manual closing ofswitch 36 will produce immediate operation of solenoids l4 and 5 tomaintain both the plant detecting device l5 and the plant removal d vicel I in their respective inoperative positions.

Operation In Figs. 1 and 4 there is shown a row of plants 46, andtractor I ii is so positioned relative to such row of plants that theelectric eye I541 located on one side of the row and light source i512on the opposite side and the lowermost position of the electric eye unit15 vertically adjusted to slightly less than the average height of theplants to be thinned. Wheel hoe H, which is disposed rearwardly of eye15, is also positioned in substantial alignment with plants '30 so thatthe lowermost one of the individual blades lid will be aligned with therow for removal of the plants as will be shortly described.

To initiate operation of the plant thinning machine, the arm 2'! israised to its maximum height position by the operators momentaryoperation of by-pass switch 36. Immediately as the tractor I0 is startedalong the row, by-pass switch 36 is opened by the operator. Thisrestores the hoe Wheel to its operating condition wherein it isrestrained against rotation by the solenoid controlled detent lid andhence the lowermost blade of the hoe wheel II will be dragged throughthe ground and. will effect the removal of each plant contacted.Concurrently, the arm 21 is gradually lowered by the force of gravityand the rate of fall of the arm is controlled by the dashpot 28. If noplant is encountered during such fall, which is of greater than averageheight, there will be no interruption of the light beam impinginguponthe photo-electric cell I50: until the plant detecting unit is droppedto approximately the average height level of the plants in the row.Immediately up on a top portion of any plant effecting an interruptionof the light beam on the photo-electric cell the trigger amplifier 35will operate to energize solenoids l4 and it through relay 35. SolenoidM withdraws the detent l lb' from engagement with the hoe wheel ll,permitting the hoe wheel H to rotate and thus save the particular plantwhich initiated the operation of the plant detecting device.Concurrently, the energization of solenoid 16 Will abruptly restore thearm 21, and hence the plant detecting unit 15 to the pre-selectedmaximum height level above the average level of the plants in the row.Such raising movement of the plant detecting device restores the fullintensity of the light beam from light source I5b impinging uponphoto-electric cell I'Ea and hence deenergizes amplifier 35 anddeactivates solenoids l4 and I6, restoring the entire apparatus to thestarting condition of the 1 cycle.

It will thus be observed that the vertical position or" the plantdetecting device it? is cyclically varied in a generally saw tooth waveconfiguration, starting with an abrupt rise to the preselected maximumheight level whenever the photo-electric cell I50; detects the topportion of an adjacent plant and then gradually lowering at a constantrate until the photo-electric cell l5a again detects the top portions ofa plant in the row. Hence, a cyclical path of movement of the plantdetecting device i5 is a set up as indicated by the dotted lines in Fig.1.

It should be particularly noted that whenever an unusually large plant,such as the plant 48a, is encountered at a point which would normally beintermediate the desired plant spacing, such large plant will be savedif it is tall enough to partially interrupt the light impinging on thephoto-electric cell [5a. It should be further noted that each plantsaved by the described apparatus becomes the reference position forstarting the desired spacing between plants so that with occasionallarger plants in the row, such larger plants are saved irrespective oftheir positions relative to the preceding saved plant of normal size,and normal spacing between the large saved plant and the next succeedingsaved plant of normal size is maintained, as best shown by the spacebetween the saved plants Mia and flb in Fig. 1.

From the foregoing description, it is clearly apparent that there ishere provided a method and apparatus for plant thinning which willselecall the plants are of relatively uniform size, will thin suchplants to an even spacing. plant thinning device is of simple, ruggedconstruction, such device will provide long service at low operatingcost. It is further pointed out that this plant thinning devicesubstantially eliminates the need for any expensive hand thinning of theplants thereby effectively reducing the cost to the farmer of raisingthe plants to maturity.

It will, of course, be understood that various details of constructionmay be varied through a wide range without departing from the principlesof this invention and it is, therefore, not the purpose to limit thepatent granted hereon otherwise than necessitated by the scope of theapepnded claims.

I claim:

1. The method of plant thinning which comprises traversing a plantremoving device along a row of plants, traversing a plant heightresponsive device along the row in advance of said plant removingdevice, interconnecting said plant removing device and said plant heightresponsive device to render said plant removing device temporarilyinoperative upon actuation of said plant height responsive device,raising the response height or" said plant height responsive device to apro-selected level above the average plant height after each actuationof the plant height responsive device, and gradually lowering the heightof said plant height responsivedevice from said pre-selected level.

2. The method of plant thinning which comprises traversing a plantdetecting device along a row of plants, said device being capable ofproducing a control action when positioned laterally adjacent anyportion of a plant, cyclically controlling the vertical position of saidplant detecting device by raising said device to a preselected levelafter each control action produced thereby and gradually lowering saiddevice until a control action is produced by one of the laterallyadjacent plants, traversing a plant removing de vice along the row ofplants immediately behind said plant detecting device and normallypositioned to remove successive plants from the row, and rendering saidplant removing device temporarily inoperative in response to the controlaction of said plant detecting device to pass over said one plantproducing said control action.

3. The method of selecting saved plants in plant thinning operationscomprising the steps of traversing a plant sensitive device along a rowof plants, said plant sensitive device being of a type capable ofproducing a control action when positioned laterally adjacent anyportion or a plant, and cyclically varying the eiiective response heightof said plant sensitive device in a generally saw tooth pattern, risingabruptly to a maximum response height above the average level of theplants and a decreasing gradually AS this J 8 to a minimum height levelsomewhat less than the average height of the plants in the row.

4. The method of selecting saved plants in plant thinning operationscomprising the steps of traversing a plant sensitive device along a rowof plants, said plant sensitive device being of a type capable ofproducing a control action when positioned laterally adjacent anyportion of a plant, raising said plant sensitive device abruptly aftereach control action to a maximum height level above the average level ofthe plants, and gradually lowering said plant sensitive device at aconstant rate from said maximum level.

5. Plant selecting mechanism for a plant thinning device comprising aportable support movable along a row of plants, a plant sensitive deviceshiitably mounted on said support for vertical movement relative to therow of plants, said plant sensitive device including means for producinga control action when positioned adjacent any portion of a plant, meansresponsive to said control action for abruptly raising said plantsensitive device to a maximum height level above the average height ofthe plants in the row, and means for gradually lowering said plantsensitive device from said maximum height level.

6. Plant selecting mechanism for a plant thinning device comprising aportable support movable along a row of plants, a photo-electric plantdetecting device shiftably mounted on said support for vertical movementrelative to the row of plants, said photo-electric device beingconstructed and arranged to produce a reaction when positioned laterallyadjacent any portion of a plant, power means responsive to said reactionof said photo-electric device and operable between said photo-electricdevice and said support for raising said photo-electric device to amaximum height level above the average height of the plants in the row,and means for gradually lowering said photo-electric device at a uniformrate from said maximum height level.

'7. Plant selecting mechanism for a plant thinning device comprising aportable support movable along a row of plants, a plant sensitive deviceshiitably mounted on said support for vertical movement relative to therow of plants, said plant sensitive device including means for producinga control action when positioned adjacent any portion of a plant, meansresponsive to said control action for abruptly raising said plantsensitive device to a maximum height level above the average height ofthe plants in the row, and means for gradually lowering said plantsensitive device at a uniform rate from said maximum height level, aplant removing device mounted on said portable support and shiftablebetween operative and inoperative positions relative to the plants inthe row, said plant removing device being normally positioned to removeall plants contacted in the row, and means responsive to said controlaction for temporarily shifting said plant removing device to its saidinoperative position for a sufiicient interval to permit said plantremoving device to pass the particular plant which produced said controlaction.

8. Plant selecting mechanism for a plant thinning device comprising aportable support movable along a row of plants, a photo-electric plantdetecting device shiftably mounted on said support for vertical movementrelative to the row of plants, said photo-electric device beingconstructed and arranged to produce a reaction when positioned laterallyadjacent any portion of a plant, power means responsive to said reactionof said photo-electric device and operable between said photo-electricdevice and said support for raising said photo-electric device to amaximum height level above the average height of the plants in the row,and means for gradually lowering said photo-electric device at a uniformrate from said maximum height level, a plant removing device mounted onsaid movable support and shiftable between operative and inoperativepositions relative to the plants in the row, said plant removing devicebeing normally positioned to remove all plants contacted in the row, andmeans responsive to said reaction for temporarily shifting said plantremoving device to its said inoperative position for a sufiicient 1Number interval to permit said plant removing device to 10 pass theparticular plant which produced said reaction.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,190,849 Berriman July 11, 1916 1,303,798 Janes May 13, 19192,177,803 Ferte et a1 Oct. 31, 1939 2,327,204 McLemore Aug. 17, 19432,507,001 Ferte May 9, 1950 2,535,720 Boncompain Dec. 26, 1950 FOREIGNPATENTS Country Date 965,868 France Feb. 22, 1950

